That God cannot will Evil

EVERY act of God is an act of virtue, since His virtue is His essence
(Chap. XCII).

2. The will cannot will evil except by some error coming to be in the
reason, at least in the matter of the particular choice there and then
made. For as the object of the will is good, apprehended as such, the
will cannot tend to evil unless evil be somehow proposed to it as good;
and that cannot be without error.* But in
the divine cognition there can be no error (Chap. LXI).
3. God is the sovereign good, admitting no intermixture of evil (Chap.
LXI).
4. Evil cannot befall the will except by its being turned away from its
end. But the divine will cannot be turned away from its end, being
unable to will except by willing itself (Chap. LXXV). It cannot therefore will evil; and thus
free will in it is naturally established in good. This is the meaning
of the texts: God is faithful and without iniquity (Deut. xxxii,
4); Thine eyes are clean, O Lord, and thou canst not look upon
iniquity (Hab. i, 13).